* {
    box-sizing: border-box;
}
body{
    background-image: linear-gradient(90deg,#7d5fff,#7158e2);

    display: flex;
    justify-content: center;/*居中*/
    align-items: center;

    height: 100vh;
    overflow: hidden;
    margin: 0;

}

.search{
    position: relative;
    height: 50px;
}
.search .input{
    background-color: #fff;
    border: 0;
    font-size: 18px;
    padding: 15px ;
    height: 50px;
    width: 50px;
    transform: width 0.3s ease;
}
.btn{
    background-color: #fff;
    border: 0;
    cursor: pointer;
    font-size: 24px;
    position: absolute;
    top: 0;
    left: 0;
    height: 50px;
    width: 50px;
    transform: transform 0.3s ease;
}
.btn:focus,
.input:focus{
    outline: none;
}
.search.active .input{
    width: 200px;
}
.search.active .btn{
    transform:translateX(198px)
}